# Pu system

> Pu system: 43 accepted literature values (crystal structure 18, invariant reaction 9, phase transition 6, formation 5) and 0 calculated phase diagram(s) from ORCHID, each value with evidence class, source, page and quote.

HTML: https://data.orchid-project.org/systems/PU.html · Markdown: https://data.orchid-project.org/systems/PU.md

43 accepted literature values from 5 paper(s) (experimental 18, model 22, unspecified 3); 0 calculated phase diagram(s). 42 further extracted value(s) not accepted by the reader-agreement checks are only in the JSON/CSV.

Data: [JSON](https://data.orchid-project.org/literature/systems/PU.json) · [CSV](https://data.orchid-project.org/systems/PU.csv) · [interactive explorer](https://orchid-project.org/data-explorer/#PU) · [papers (bibliography)](https://data.orchid-project.org/bibliography/pages/systems/PU.html) · [Markdown](https://data.orchid-project.org/systems/PU.md)

Table: Accepted values by evidence class

| Evidence class | Values |
|---|---:|
| experimental | 18 |
| model | 22 |
| unspecified | 3 |

Table: Accepted values by property group

| Property group | Values |
|---|---:|
| invariant reaction | 9 |
| phase transition | 6 |
| formation | 5 |
| heat capacity / entropy / enthalpy | 5 |
| crystal structure | 18 |

## Invariant reactions (literature)

Table: Invariant reactions reported in the literature for the Pu system (9)

| T (K) | Reaction / phases | Compositions (mole fraction) | Class | Source | Location | Quote |
|---:|---|---|---|---|---|---|
| 593 | δ-Pu = γ-Pu |  | model | [1] Guéneau 2008 | Table 3, p. 9, row 43; `ORC-2VSQ3ZVQFH` |  |
| 488.15 | polymorphic: (γPu) ↔ (βPu) | (γPu):  | model | [2] Liu 2014 | Table 4, p. 4, row 11; `ORC-4MNV2TFB5D` |  |
| 488.15 | polymorphic: (γPu) ↔ (βPu) | (γPu):  | experimental | [2] Liu 2014; _cites Massalski 1990_ | Table 4, p. 4, row 10; `ORC-FROHBYN2XB` |  |
| 488 | γ-Pu = β-Pu |  | model | [1] Guéneau 2008 | Table 3, p. 9, row 44; `ORC-O3KEQGXHW2` |  |
| 398.15 | polymorphic: (βPu) -> (αPu) | (βPu): Pu 1; (αPu): Pu 1 | experimental | [2] Liu 2014; _cites Okamoto 2000_ | Table 5, p. 6, row 24; `ORC-2C2FV64NJO` |  |
| 398.15 | polymorphic: (βPu) ↔ (αPu) |  | experimental | [2] Liu 2014; _cites Massalski 1990_ | Table 4, p. 4, row 12; `ORC-AZAZCY6ZYD` |  |
| 398.15 | polymorphic: (βPu) ↔ (αPu) | (βPu):  | model | [2] Liu 2014 | Table 4, p. 4, row 13; `ORC-Y2K6IGWJOC` |  |
| 398.15 | polymorphic: (βPu) -> (αPu) | (βPu): Pu 1; (αPu): Pu 1 | model | [2] Liu 2014 | Table 5, p. 6, row 25; `ORC-Z6LHBSGBRJ` |  |
| 398 | β-Pu = α-Pu |  | model | [1] Guéneau 2008 | Table 3, p. 9, row 45; `ORC-YKFNU4E63F` |  |

## Formation enthalpies

Literature values in kJ/mol-atom where the per-atom basis is known. DFT columns: the lowest-energy entry at the same composition (Materials Project 2026.04.13, OQMD v1.8; different energy references, never averaged), from [dft_parity.json](https://data.orchid-project.org/literature/dft_parity.json).

Table: Enthalpies of formation, Pu system (5)

| Phase | Compound | Value | T (K) | Class | MP DFT (kJ/mol-atom) | OQMD DFT (kJ/mol-atom) | Source | Location | Quote |
|---|---|---:|---:|---|---:|---:|---|---|---|
| α-Pu |  | 0 kJ/mol-atom | 298.15 | model |  |  | [3] Beneš 2014 | Table 1, p. 2, row 13; `ORC-WNIUEJTMOK.8cba78` |  |
| β-Pu |  | 3.8809 kJ/mol-atom | 298.15 | model |  |  | [3] Beneš 2014 | Table 1, p. 2, row 16; `ORC-BDHFFZ5JQY.7e83e9` |  |
| γ-Pu |  | 4.4525 kJ/mol-atom | 298.15 | model |  |  | [3] Beneš 2014 | Table 1, p. 2, row 19; `ORC-T3FEWFB2GR.230a78` |  |
| δ-Pu |  | 5.0503 kJ/mol-atom | 298.15 | model |  |  | [3] Beneš 2014 | Table 1, p. 2, row 23; `ORC-A5JIFDBHWC.fcba1d` |  |
| ϵ-Pu |  | 7.5591 kJ/mol-atom | 298.15 | model |  |  | [3] Beneš 2014 | Table 1, p. 2, row 30; `ORC-H46OTICAF7.32e1b1` |  |

## Other properties

### Phase transition (6)

Table: Phase transition, Pu system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Phase transition | 397.15 K | 397.15 | α-Pu; _alloy: Pu 1_ | model | [4] Perron 2016; _cites Dinsdale 1991_ [doi](https://doi.org/10.1016/0364-5916%2891%2990030-n) | Table 1, p. 3, row 6; `ORC-BVUS6KHZIO` |  |
| Phase transition | 488.15 K | 488.15 | β-Pu; _alloy: Pu 1_ | model | [4] Perron 2016; _cites Dinsdale 1991_ [doi](https://doi.org/10.1016/0364-5916%2891%2990030-n) | Table 1, p. 3, row 7; `ORC-FAA2H5P4FC` |  |
| Phase transition | 593.15 K | 593.15 | γ-Pu; _alloy: Pu 1_ | model | [4] Perron 2016; _cites Dinsdale 1991_ [doi](https://doi.org/10.1016/0364-5916%2891%2990030-n) | Table 1, p. 3, row 8; `ORC-7PC4GFYCFJ` |  |
| Phase transition | 736.15 K | 736.15 | δ-Pu; _alloy: Pu 1_ | model | [4] Perron 2016; _cites Dinsdale 1991_ [doi](https://doi.org/10.1016/0364-5916%2891%2990030-n) | Table 1, p. 3, row 9; `ORC-YPOTACSDYH` |  |
| Phase transition | 756.15 K | 756.15 | δ′-Pu; _alloy: Pu 1_ | model | [4] Perron 2016; _cites Dinsdale 1991_ [doi](https://doi.org/10.1016/0364-5916%2891%2990030-n) | Table 1, p. 3, row 10; `ORC-RVG2B33M4R` |  |
| Phase transition | 913.15 K | 913.15 | ε-Pu; _alloy: Pu 1_ | model | [4] Perron 2016; _cites Dinsdale 1991_ [doi](https://doi.org/10.1016/0364-5916%2891%2990030-n) | Table 1, p. 3, row 11; `ORC-PFELX26B5B` |  |

### Heat capacity / entropy / enthalpy (5)

Table: Heat capacity / entropy / enthalpy, Pu system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Entropy; _printed: S0(298.15)_ | 54.461 J/mol-atom/K | 298.15 | α-Pu | model | [3] Beneš 2014 | Table 1, p. 2, row 13; `ORC-WNIUEJTMOK.ee59dc` |  |
| Entropy; _printed: S0(298.15)_ | 64.266 J/mol-atom/K | 298.15 | β-Pu | model | [3] Beneš 2014 | Table 1, p. 2, row 16; `ORC-BDHFFZ5JQY.acb2bf` |  |
| Entropy; _printed: S0(298.15)_ | 65.477 J/mol-atom/K | 298.15 | γ-Pu | model | [3] Beneš 2014 | Table 1, p. 2, row 19; `ORC-T3FEWFB2GR.f11976` |  |
| Entropy; _printed: S0(298.15)_ | 66.37 J/mol-atom/K | 298.15 | δ-Pu | model | [3] Beneš 2014 | Table 1, p. 2, row 23; `ORC-A5JIFDBHWC.d55d64` |  |
| Entropy; _printed: S0(298.15)_ | 69.975 J/mol-atom/K | 298.15 | ϵ-Pu | model | [3] Beneš 2014 | Table 1, p. 2, row 30; `ORC-H46OTICAF7.b7c31a` |  |

### Crystal structure (18)

Table: Crystal structure, Pu system

| Property | Value | T (K) | Phases / composition | Class | Source | Location | Quote |
|---|---:|---:|---|---|---|---|---|
| Lattice a | 11.83 Å |  | β-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Zachariasen 1963_ [doi](https://doi.org/10.1107/s0365110x63002012) | Table 1, p. 2, row 2; `ORC-XIXOUSUYVA.a06a9a` |  |
| Lattice a | 6.183 Å ± 0.001 | 298.15 | α-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Zachariasen 1963_ [doi](https://doi.org/10.1107/s0365110x63002012) | Table 1, p. 2, row 1; `ORC-EQHP34FLH5.1def36` |  |
| Lattice a | 3.1587 Å ± 4.000e-4 | 298.15 | γ-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Zachariasen 1955_ [doi](https://doi.org/10.1107/s0365110x55001357) | Table 1, p. 2, row 3; `ORC-U242FFURH2.b284a0` |  |
| Lattice a | 0.46347 not_printed | 298.15 | δ-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Ellinger 1956_ | Table 1, p. 2, row 4; `ORC-2GI76F5ZOK` |  |
| Lattice a | 3.339 Å ± 0.003 | 298.15 | δ′-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Ellinger 1956_ | Table 1, p. 2, row 5; `ORC-CIUHREYHWX.c3f59e` |  |
| Lattice a | 0.36375 not_printed | 298.15 | ε-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Ellinger 1956_ | Table 1, p. 2, row 6; `ORC-JL7B32IUOF` |  |
| Lattice b | 10.449 Å |  | β-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Zachariasen 1963_ [doi](https://doi.org/10.1107/s0365110x63002012) | Table 1, p. 2, row 2; `ORC-XIXOUSUYVA.539a8f` |  |
| Lattice b | 4.822 Å ± 0.001 | 298.15 | α-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Zachariasen 1963_ [doi](https://doi.org/10.1107/s0365110x63002012) | Table 1, p. 2, row 1; `ORC-EQHP34FLH5.c00e50` |  |
| Lattice b | 5.7682 Å ± 4.000e-4 | 298.15 | γ-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Zachariasen 1955_ [doi](https://doi.org/10.1107/s0365110x55001357) | Table 1, p. 2, row 3; `ORC-U242FFURH2.2e749a` |  |
| Lattice c | 9.227 Å |  | β-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Zachariasen 1963_ [doi](https://doi.org/10.1107/s0365110x63002012) | Table 1, p. 2, row 2; `ORC-XIXOUSUYVA.0303cc` |  |
| Lattice c | 10.963 Å ± 0.001 | 298.15 | α-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Zachariasen 1963_ [doi](https://doi.org/10.1107/s0365110x63002012) | Table 1, p. 2, row 1; `ORC-EQHP34FLH5.699bdc` |  |
| Lattice c | 10.162 Å ± 0.002 | 298.15 | γ-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Zachariasen 1955_ [doi](https://doi.org/10.1107/s0365110x55001357) | Table 1, p. 2, row 3; `ORC-U242FFURH2.25f3f0` |  |
| Lattice c | 4.446 Å ± 0.007 | 298.15 | δ′-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Ellinger 1956_ | Table 1, p. 2, row 5; `ORC-CIUHREYHWX.e05ebb` |  |
| Molar volume; _printed: V_ | 13.75 cm^3 mol^-1 |  | B.c.c.; _alloy: Pu 1_ | unspecified | [5] Ogawa 1993 | Table 1, p. 2, row 8; `ORC-RLE2DSNMDP` |  |
| Molar volume; _printed: V_ | 15.02 cm^3 mol^-1 |  | F.c.c.; _alloy: Pu 1_ | unspecified | [5] Ogawa 1993 | Table 1, p. 2, row 9; `ORC-OYNTGO45EI` |  |
| Molar volume; _printed: V_ | 14.53 cm^3 mol^-1 |  | Liquid; _alloy: Pu 1_ | unspecified | [5] Ogawa 1993 | Table 1, p. 2, row 7; `ORC-ZKQLLC4PZV` |  |
| lattice beta | 138.65 ° |  | β-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Zachariasen 1963_ [doi](https://doi.org/10.1107/s0365110x63002012) | Table 1, p. 2, row 2; `ORC-XIXOUSUYVA.77f72e` |  |
| lattice beta | 101.79 ° | 298.15 | α-Pu; _alloy: Pu 1_ | experimental | [1] Guéneau 2008; _cites Zachariasen 1963_ [doi](https://doi.org/10.1107/s0365110x63002012) | Table 1, p. 2, row 1; `ORC-EQHP34FLH5.2709e6` |  |

## Sources

Reporting papers the values were read from (a value cited from another work names that work in its row).

1. Christine Guéneau, Christian Chatillon, Bo Sundman, Thermodynamic modelling of the plutonium–oxygen system, Journal of Nuclear Materials 378, 257-272 (2008). [doi:10.1016/j.jnucmat.2008.06.013](https://doi.org/10.1016/j.jnucmat.2008.06.013)
2. X.J. Liu, Q. He, D. Wang, Y. Lu, M.H. Chen, J.P. Jia et al., Thermodynamic assessments of the Pu–Zn and La–Pu systems, Journal of Nuclear Materials 453, 169-175 (2014). [doi:10.1016/j.jnucmat.2014.07.001](https://doi.org/10.1016/j.jnucmat.2014.07.001)
3. O. Beneš, D. Manara, R.J.M. Konings, Thermodynamic assessment of the Th–U–Pu system, Journal of Nuclear Materials 449, 15-22 (2014). [doi:10.1016/j.jnucmat.2014.02.001](https://doi.org/10.1016/j.jnucmat.2014.02.001)
4. A. Perron, P.E.A. Turchi, A. Landa, B. Oudot, B. Ravat, F. Delaunay, Thermodynamic assessments and inter-relationships between systems involving Al, Am, Ga, Pu, and U, Journal of Nuclear Materials 482, 187-200 (2016). [doi:10.1016/j.jnucmat.2016.09.012](https://doi.org/10.1016/j.jnucmat.2016.09.012)
5. Toru Ogawa, Alloying behaviour among U, Np, Pu and Am predicted with the Brewer valence bond model, Journal of Alloys and Compounds 194, 1-7 (1993). [doi:10.1016/0925-8388(93)90636-2](https://doi.org/10.1016/0925-8388%2893%2990636-2)

## Please cite

- R. Arróyave, J. Saal, D. Shin, ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature (version 2026.10; Version 1, machine-extracted), Zenodo (2026). https://doi.org/10.5281/zenodo.23735569
- R. Arróyave, J. Saal, D. Shin, ORCHID data: umbrella record of the ORCHID datasets (version 2026.10; Version 1, machine-extracted), Zenodo (2026). https://doi.org/10.5281/zenodo.23736065

Also cite the original source of every value you use (paper_citation / paper_doi, and cited_dois for values the paper cites from earlier work); B. Hallstedt, The SGTE collection of binary datasets, Calphad 89 (2025) 102833, https://doi.org/10.1016/j.calphad.2025.102833 (CC BY 4.0), and the original assessment named in each file; A. Jain et al., The Materials Project: A materials genome approach to accelerating materials innovation, APL Materials 1 (2013) 011002, https://doi.org/10.1063/1.4812323 (CC BY 4.0); J. E. Saal et al., JOM 65 (2013) 1501, https://doi.org/10.1007/s11837-013-0755-4 and S. Kirklin et al., npj Comput. Mater. 1 (2015) 15010, https://doi.org/10.1038/npjcompumats.2015.10 (CC BY 4.0).

Version 1, machine-extracted: values were read by language-model readers constrained to quote their source and checked automatically, and the release was then audited on the printed pages by adversarial audits, an independent second review of fit-facing records and a preliminary human review of a frozen sample. Flags such as accepted and ESPEI-ready record screening results, not certification; known issues are listed in the release notes.

```bibtex
@misc{orchid_literature_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID-Values: thermodynamic and phase-equilibrium values read from the literature}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23735569},
  url       = {https://doi.org/10.5281/zenodo.23735569},
  note      = {Version 1, machine-extracted}
}

@misc{orchid_data_2026,
  author    = {Arr{\'o}yave, Raymundo and Saal, James and Shin, Dongwon},
  title     = {{ORCHID data: umbrella record of the ORCHID datasets}},
  version   = {2026.10},
  publisher = {Zenodo},
  year      = {2026},
  doi       = {10.5281/zenodo.23736065},
  url       = {https://doi.org/10.5281/zenodo.23736065},
  note      = {Version 1, machine-extracted}
}
```

---

Derived data CC BY 4.0 ([licence](https://creativecommons.org/licenses/by/4.0/)): cite ORCHID ([CITATION.cff](https://data.orchid-project.org/CITATION.cff)) and the original sources. Quotes are short excerpts kept so that each value can be checked; they remain under the publishers' copyright and are not relicensed. Source papers, page images and full text are not redistributed. Field reference: [SCHEMA.md](https://data.orchid-project.org/literature/SCHEMA.md). Machine-readable guide: [llms.txt](https://data.orchid-project.org/llms.txt). Found an error? The report link of a value (Markdown: its id, ORC-..., in the Location column) opens a pre-filled GitHub issue, https://github.com/orchid-calphad/orchid-data/issues/new?template=report-value-error.yml&record_id=\<id>, carrying only the record id, source and value; [how to contribute](https://orchid-project.org/contribute/).